1. Field of the Invention
The present invention relates to earth boring systems.
2. Description of the Prior Art
Earth boring systems are used for sinking shafts, and such systems typically use large unitary stages suspended by cables and moved by one or more winches. A stage is generally a multi-decked apparatus with platforms to hold equipment, supplies or workers.
The process of sinking shafts involves the steps of drilling a hole from the stage, placing an explosive charge in the hole and then detonating the charge. The resultant broken rock is removed with a bucket system, and thereafter the process is repeated. The shaft wall is often reinforced with a lining to minimize the chances of the shaft caving in, this step is performed from the stage.
The stage is moved to various positions along the shaft by a winch and cables. This process is labour intensive and dangerous work and the winch, sheaves and cable require careful and continuous monitoring and maintenance.
Other drawbacks are that the stage is subject to bounce from cable stretch, which leads to costly and time consuming process of doubling down cable procedure, difficulty and expense of periodic rope inspection and the depth restriction of cables for stages due to cable safety factors.